The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Thermostatic mixers that are suited to handle a large flow rate generally do not function if the flow rate required from them is considerably smaller than the maximum flow rate they are designed for, as occurs, for example, when a thermostatic mixer suited to supply a fixture comprising a plurality of showers is used to supply a single shower. Under these circumstances, the thermostatic mixers lose their stability and start to vibrate so that the water flow drawn from them is subject to constant fluctuations in the ratio between cold water and warm water and therefore sustains temperature fluctuations, which are uncomfortable for the user and may become dangerous. This disadvantage may be corrected by opposing a resistance to the cold water flow fed into the thermostatic mixer when small flow rates of mixed water are supposed to be pumped and by suppressing or reducing this resistance when large flow rates of mixed water are supposed to be pumped. This operation is carried out automatically by devices for dynamic flow regulation, which are designed to reduce the passage cross-section provided to the arriving cold water when the accommodated flow rate is reduced and to restore a larger passage cross-section when an increased flow rate is required.
Nevertheless, the known devices for dynamic flow regulation are generally associated with various disadvantages. Above all, in light of their design and their dimensions, they must be elements that can be added to the fixture in series connection to the feed pipe of the cold water to the mixer and which cannot be installed in the mixer itself. Therefore, the load of the recuperating spring requires adjustment as a function of the inflow pressure of the cold water for the device to function properly. Consequently, during installation the device must be adapted to the pressure conditions prevailing in the system, and the function of the device is no longer appropriate when considerable fluctuations in the cold water inflow pressure occur.